1. Field of the Invention
The present invention relates to a load-lock apparatus, a device manufacturing apparatus, which includes the load-lock apparatus, and a device manufacturing method that manufactures a device using the device manufacturing apparatus.
2. Description of the Related Art
Generally, a semiconductor device is manufactured by subjecting a wafer to various types of processes. Processing chambers used for the respective processes form environments suitable to the processes.
An exposure apparatus which transfers a micropattern, such as a circuit pattern onto a semiconductor wafer or a substrate, such as a liquid crystal display substrate, requires a finer transfer pattern and a higher throughput. To obtain the finer transfer pattern, the exposure apparatus must use exposure light having a shorter wavelength. An exposure light source is shifting from a 365-nm i-line light source to a 248-nm KrF excimer laser source, and to a 193-nm ArF excimer laser source. Furthermore, a 157-nm F2 excimer laser source and an EUV (Extreme Ultra Violet) light source, which are shorter-wavelength light sources, have been developed.
An ArF excimer laser beam, an F2 excimer laser beam, and EUV light attenuate largely in the atmosphere. Hence, the exposure unit of the exposure apparatus is stored in an exposure chamber. The exposure chamber forms a reduced-pressure space where the laser beam does not attenuate largely, or a purged space, which is purged with an inert gas, such as N2 or He.
The exposure chamber which forms the reduced-pressure space or purged space connects to a load-lock chamber to load or unload a wafer or reticle efficiently. The wafer or reticle is loaded from the external space into the exposure chamber or unloaded from the exposure chamber to the external space through the load-lock chamber.
When loading the wafer or reticle from the external space into the exposure chamber, first, it is loaded into the load-lock chamber, and after that, a gate valve isolates the interior of the load-lock chamber from the external space. Then, the interior of the load-lock chamber is pressure-reduced or purged with an inert gas. After that, a gate valve between the load-lock chamber and the exposure chamber is opened, to load the wafer or reticle from the load-lock chamber into the exposure chamber. When unloading the wafer or reticle from the exposure chamber, first, it is unloaded from the exposure chamber to the load-lock chamber, and after that, the gate valve isolates the interior of the load-lock chamber from the exposure chamber. Then, the gate valve between the load-lock chamber and the external space is opened, so the load-lock chamber is open to the atmosphere. The wafer or reticle is unloaded to the external space through the open gate valve.
According to Japanese Patent Laid-Open No. 2003-86668, a lid having a spacer and a lid not having a spacer are prepared as lids for hermetically closing a load-lock chamber. The volume in the load-lock chamber is changed by selecting one of these lids. Also, according to Japanese Patent Laid-Open No. 2003-86668, spacers having different volumes are prepared. The spacers are selectively used.
In the arrangement disclosed in Japanese Patent Laid-Open No. 2003-86668, the spacer changes the volume of the load-lock chamber in accordance with the number of connected wafer cassettes, which are to be loaded into the load-lock chamber, in the connected state. Hence, Japanese Patent Laid-Open No. 2003-86668 does not disclose or suggest any idea of changing the volume in the load-lock chamber where the wafer cassettes have been loaded, or a substrate has been loaded.